This invention relates to alarm devices designed for use in swimming pools and similar small bodies of water.
One type of swimming pool alarm includes a transducer for picking up sounds from the water and a bell or alarm that is triggered when sounds in the water exceed a predetermined level. Such devices generally do not work well in normal use because they are either too sensitive or not sensitive enough. Moderately sensitive pool alarms may be set off by loud noises, such as nearby traffic or clapping of the hands, or by electromagnetic waves generated by nearby power lines. If the sensitivity is reduced to prevent false alarms, then the device may not be triggered by a moderately loud splash such as if a child falls into the pool at an end thereof opposite the transducer. Actually, many pool accidents could be avoided if the alarm would sound when a child merely waves his hands in the water near the side of the pool. Previous pool alarms could not detect such a slight disturbance without being so sensitive as to be repeatedly set off by ambient non-pool noises.